Presently scientist are conducting research to help people gain new techniques in swimming. While scientists continue research for new swimming techniques, they must start with early techniques of swimming as a sport and part of life. Learning how to swim is not easy. However, swimming is physics. There are laws, buoyancy, drags, and motions. To become a good swimmer one should take initiative to learn how certain techniques evolved and take an active approach into applying these physics into their own strokes. This report will state a brief summary of the physics of swimming and its mechanics and then continue by describing the technique of the freestyle and backstrokes.
A beginner swimmer must learn how to float in water. This is known as buoyancy, water that exerts an upward force against an object to the weight of the water that would be pushed aside by the object. For example, take three glass bottles the same size, each bottle weighs one pound and can hold five pounds of water. Leave one bottle empty, seal it, and place it in water. Now the bottle floats high in the water with the majority of the bottle above the surface. Then take the second bottle, fill it with three pounds of water, and place the bottle in the water. Second bottle will float vertical in the water. Finally, put five pounds of water in the third bottle and insert it into the water. The third bottle will sink to the bottom but will sink vertical. Therefore, first bottle floats because it weighs one pound but pushes aside ten pounds of water. Thus, it would take some effort to push the empty bottle underwater. This is called buoyancy. The second bottle also floats but floats vertical because three pounds displaces the five pounds of water. Although the third bottle sinks, buoyancy is still a factor. Thus the bottle is sinking but it is sinking upward. This is known as specific gravity.
Form drag is resistance to the shape of an object and its profile to the water. For example, narrow water skis would pass through water more efficiently than a wider water ski. The narrow water ski pushes less water aside than the wider skis. Second example to reduce drag is the streamlined position. To feel the difference, push off from the wall of the pool and try gliding in various positions: streamlined, with your arms out to the sides, and with your knees flexed. As you increase the surface area the water must pass around, you increase from drag and cannot glide as far. Wave drag is resistance caused by water turbulence. Wave drag also occurs during speed of the swimmer. The faster the swimmer swims the faster the wave drag occurs in the pool. A swimmer can reduce wave drag by smooth process of strokes but one must not use splashing arm entries to reduce wave drag. On the other hand, swimmers can create wave drag; thus, lane lines have been created to reduce drag. A frictional drag is the resistance caused by the surface texture of the body as it moves through the water. For example, to reduce frictional drag competitive swimmers shave their body hairs to reduce frictional drag. This method is thought to increase the speed of swimmers and reduce frictional drag.
Lift is a force produced perpendicular to the flow of a fluid. It is predicted by Bernoulli’s equation for any obstacle which compresses streamlines at one boundary and compresses them on the opposite one, resulting in a difference in pressures which causes the lift force. Doc “Counsilman’s lift theory promoted the use of curvilinear motions to produce propulsion. In the lift model, the hand formed an airplane-type wing that, when moved sideways to the direction of travel, created lift” (Adams, 2000). ” ‘The choice between Bernoulli’s or Newton’s model in predicting dynamic lift,’ lay bare the arguments supporting lift as the primary or even a significant force in swimming. (Ernie) Maglischo is now reconsidering lift theory and is revisiting (Charles) Silvia’s ideas” (Adams, 2000). It is therefore in question whether lift theory is important to swimming and if so, how important is it?
The law of inertia states that a force is needed to move a body at rest, to stop a body that is moving or to change the direction of a moving body. The law of inertia affects aquatics in two aspects. First static inertia is the tendency of a body at rest to stay at rest. Swimmer must overcome every time he or she enters a pool because the static inertia of the water will resist any effort change position. Secondly, dynamic inertia is the tendency of a moving body to keep moving. To overcome the law of inertia, swimmers must possess energy to complete a stroke to keep moving. Furthermore, dynamic inertia lets swimmers rest because your body is moving. However, if one rest to long during dynamic inertia, one might have to overcome static inertia.
The law of acceleration states that the speed of a body depends on how much force is applied to it and the direction of that force. The law of acceleration is relevant in swimming in two ways. First, the more force you apply to a stroke, the faster a swimmer will swim. Second, swimming is more efficient when a swimmer chooses to stay in a chosen direction when all your propulsive force is in the same direction.
The law of action and reaction states, that for every action there is an equal and opposite reaction. Reaction and action can occur in water and land. For instance, if a ball drops into a bucket of water, the ball stops in the water and the water will project from the bucket. Thus, it is creating an action and reaction from the ball. A second example, when one dives from a diving board, the board reacts to the force of your feet acting against it so you can take off for the dive.
The law of levers is the product of force and force arm is equal to the product of the resistance and resistance. The law of levers for swimming can be demonstrated in the arm stroke and the front crawl. Arm muscles provide the force and the shoulder is the pivot point. Water is the resistance, which comes from the arm during the strokes. The way to improve leverage is to use less force when swimming. For example, the front crawl a swimmer can perform this by bending the elbow, this reduces the force when needed.
Front crawl or freestyle is both the fastest and the most efficient swimming technique. The ideal body position for the front crawl is having your body horizontal, with your body stretched out in a straight line. Your face should be in the water, except when you come up for air, with the water at about the hairline. You should look forward and slightly downward. The arm stroke for the front crawl is generally one arm pushing back, and the other arm coming from your side. In the front crawl, the arms provide about 80 percent of the propulsion, more than any other stroke. The best way to use your arms efficiently is in an elongated arm pull. This gives you better propulsion on the water because you are always pushing against still water rather than water that is already in motion. There are five phases in the arm stroke: 1. Entry 2. Catch 3. Pull 4. Follow-through 5. Recovery. Two important things to remember when learning the stroke: 1. Keep elbows high 2. Accelerate your hand speed until you have completed the follow-through.
The leg kick generally performed using this method of swimming is the “flutter” kick. The flutter kick provides only about 20 percent of the propulsion. To do the flutter kick, move your legs up and down alternately in a steady, strong, constant motion. As you kick downward, bend your knee slightly and keep your ankle loose. As you kick upward, hold your knee relatively straight and raise your foot until your heel breaks the water surface. If you bring your feet too far out of the water, may make a big splash, and contributes nothing to the propulsion of your body. Your legs should only go twelve to sixteen inches below the surface of the water. Another method of kicking done after leaving the wall is kicking on your side. This method first began with Misty Hyman.
The theory behind Hyman kicking underwater on her side is based on the belief that a swimmer can fill the water with energy releasing vortices. The impetus for this unorthodox maneuver was based on an article published in the March 1995 issue of Scientific American, titled An Efficient Swimming Machine. In the article, authors Michael and George Triantafyllou share their research findings on how fish utilize spinning eddies to boost their swimming speed (Rutemiller, 1996).
Breathing for the front crawl can be a bit provoking for people new to this style of stroke. Some people twist their heads from side to side with every stroke, causing their bodies to do too much unnecessary movement. The concept for breathing requires some coordination with the roll of your body. As your body rolls toward your breathing side, turn your head gently and take a deep breath. By doing this when you roll, you will not need to lift your head out of the water. After you inhale, return your face into the water and exhale slowly as your body rolls toward the other side. Make sure before you turn to the other side, to exhale completely so that you are not trying to exhale and get air in a short amount of time. Coordination of all of the components is pieced together as such. One arm enters the water as the other begins the recovery with a bent elbow.
Good swimmers bend the elbow during the pull to place the body in a strong position. In this position the strong medial rotations of the arm, e.g. the pectorals, can be used. In contrast poor swimmers tend to have a straight arm or else ‘drop the elbow’. In both cases the strong muscles are not being used adequately, the lever system is poor, and the forces produced are not in the desired direction throughout the pull (Sanders, 2000).
The legs kick up and down in a steady flutter kick throughout the stroke. After the catch is made, the swimmer enters the most propulsive phase of the stroke. The movement should be “the same movement a gymnast would use in performing the iron cross on the still rings. The only difference between the gymnastic and swimming actions is in the flexion of the swimmer’s elbows to increase the mechanical advantage of the arm’s lever system. This position also fits beautifully the position needed to apply force backward with the hand and forearm that is required in the drag theory of propulsion” (Adams, 2000). The elbow is held high and the body has begun to roll. As the body rolls, the pulling arm passes under the chest and the elbow achieves its maximum bend. The other arm prepares to enter the water, directly in front of the shoulder. As the swimmer completes the pull with the follow-through, he or she begins to rotate his or her head to the recovering side to inhale. As the swimmer inhales, his or her body achieves its maximum roll. His or her other hand enters the water to begin the next stroke. The overall idea is to achieve maximum results with minimal effort. “Good swimmers avoid wasting energy by allowing muscles to relax during the non-propulsive parts of the arm and leg actions. Poorer swimmers over-control their recovery in an attempt to maintain good form whereas good swimmers have a very relaxed appearance during the arm recovery” (Sanders, 2000).
The flippered simmer (Ian Thorpe) has the sensation that the arm stroke is too easy, especially during the early positioning phase of the stroke. It is my opinion that this is what Ian Thorpe must feel as he swims. And, knowing the size (17) and flexibility exhibited in Thorpe’s feet, the advantage of superior body structure only adds to an already efficient technique. The inertial and non-muscular nature of two-thirds of Ian Thorpe’s stroke (the recovery and catch phases) adds to the endurance of the swimmer (Adams, 2000).
The back crawl or backstroke is one of the most peculiar of the four major swimming strokes. It is the only stroke that is done upside-down. The only downside to using the backstroke is that the swimmer cannot see where they are going, only where they have been. The body position for the backstroke, the swimmer should adopt as streamlined a body position as possible. Try thinking of lying flat on your back in bed without a pillow. The ideal backstroke body position is the placement of the hips. Your hips should be a few inches below the surface of the water. If the hips are too low, your legs will drop and you will create an excess drag. If held too high, your legs will ride too high and much of the kick will be out of the water. The position of the hips is determined mainly by how you hold your head. Your head should be in such a way that the ears are barely submerged and the waterline is about at the middle of your head and below your chin. Your head should be in an almost straight alignment with your body. To maintain this position, keep your eyes open and focus on an object about forty-five degrees above the surface of the water. If your head is too far back, your hips will rise and your legs will follow. If your head is too far forward, your hips will drop, causing a lot of unnecessary resistance.
The arm stroke for the backstroke has the same concept as the arm stroke for the front crawl. Use the first arm, then the other in a continuous, flowing, and almost rhythmic motion. It is important to push against water that is not moving. To do this with the most efficient results, your hands must describe the same elongated pattern as in the front crawl. As you start the stroke, your arm is extended straight backward and your hand enters the water directly above your shoulder. It is important to remember to have your palm facing outward. A common mistake is having the palms facing inwards, which causes unnecessary resistance. As the arm enters the water, its momentum will carry it about eight to twelve inches below the surface before you begin to push backwards. Having a bent elbow and a natural body roll can greatly contribute to the execution of the backstroke.
The backstroke uses the same “flutter” kick as the front crawl. Because you are swimming on your back, it is the upbeat, not the downbeat, phase of the kick that provides most of the propulsion for the swimmer. The kick not only propels you, but also stabilizes the body position. The most efficient kick to use is the six-beat kick – six kicks of the legs for every complete cycle of the arms. During the upbeat phase, the knee should be bent with the toes turned slightly inward. During the downbeat, the knee should be kept straight. The good thing to the backstroke kick is that is natural and comes easily to most people. Because the head is above water at all times, there is really no breathing method, other than to establish a consistent breathing pattern. Inhale and exhale once during each arm cycle. If your breathing is not consistent, you may start breathing too shallowly and start to pant. Coordination of all the pieces is put together as such. The left arm enters the water at a point directly over the shoulder. The legs are kicked up and down in the flutter kick. The left arm sinks downward as the pull begins and while the right arm starts its recovery directly upward. The elbow of the pulling arm pushes backward and downward, while the legs continue their flutter kick. The pull ends with the palms pressing water toward the bottom of the pool, while the recovering arm enters the water in a line directly over the shoulder.
In conclusion, swimming is becoming a very scientific sport. The laws of physics are being applied to the technique of the strokes in an attempt to achieve better results. The theories on how to apply these laws may differ but the results are clear. World record times are being lowered more than ever. Perfecting technique and training methods are evolving to an ever-changing sport. For example, Brooke Bennett’s coach “use(s) a set of 10 x 300 meter swims with 20 seconds rest, during which period the swimmers take their pulse and (he) record(s) their times and heart rates. The swims are done at a consistent level of effort with the swimmers instructed to maintain the highest possible heart rate” (Banks, 1997). This method can be done to achieve anaerobic threshold. Another method to achieve this is hypoxic training in which the swimmer controls how often they breath, usually only a couple of times for each 25 meters. Once both the stroke technique and the training methods are optimal for swimmer then the swimming is at its best.